Variable costs are costs that:

a. Vary in total directly and proportionately with changes in the activity level.

b. Remain the same per unit at every activity level.

c. Neither of the above.

d. Both (a) and (b) above.

The relevant range is:

a. The range of activity in which variable costs will be curvilinear.

b. The range of activity in which fixed costs will be curvilinear.

c. The range over which the company expects to operate during a year.

d. Usually from zero to 100% of operating capacity.

Mixed costs consist of a:

a. Variable cost element and a fixed cost element.

b. Fixed cost element and a controllable cost element.

c. Relevant cost element and a controllable cost element.

d. Variable cost element and a relevant cost element.